A new type of image sensor integrates an optical phase grating with a photodetector array. The phase grating produces an interference pattern that is unintelligible to a human observer, but that nevertheless includes intensity and spatial-frequency information that can be processed to recover an image or other information of interest in the imaged scene. For example, U.S. Patent Publication 2015/0061065 to Patrick R. Gill and David G. Stork, incorporated herein, describes image sensors with phase anti-symmetric gratings that, with processing, can acquire images and image data without a lens.
Eliminating the requirement for a lens can greatly reduce the size and cost of image sensors. These savings are of particular interest in infrared (IR) imaging systems because the materials used in the manufacture of IR lenses (e.g., monocrystalline Germanium) are generally expensive relative to those for visible light, and the cost of IR lenses tends to scale with the cube of their linear size.